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NTSB Report
January 8, 1989 · Bell 206B III · N16733
Park City, UT
Overview
Report Status
Probable Cause
Event Type
Accident
Date
January 8, 1989
Injury Outcomes
No injuries (1 uninjured)
Location
Park City, UT
Aircraft
Bell 206B III
Tail Number
N16733
Operator
Avman
Injuries
None
Aircraft Damage
Substantial
NTSB Number
DEN89LA059
THE COMMERCIAL PLT FLEW A RESCUE TEAM TO A MOUNTAIN AVALANCHE AREA. THE TEAM DEPLANED AND DURING THE UNLOADING PROCEDURE THE HELICOPTER SETTLED BACKWARDS INTO LOOSE SNOW. THE PLT ADDED COLLECTIVE PITCH AND ATTEMPTED TO HOVER. AS THE HELICOPTER LEFT THE GROUND, AN UNCOMMANDED RIGHT SPIN BEGAN. THE PLT PERFORMED A HOVERING AUTOROTATION 30 FEET AWAY FROM THE GROUND PERSONNEL. AT TOUCHDOWN THE TAIL BOOM ENTERED DEEP SNOW AND THE ACFT CAME TO REST NOSE HIGH. THE PLT DISCOVERED THE TAIL ROTOR SHAFT HAD BROKEN FORWARD OF THE TAIL ROTOR GEAR BOX. A POST ACCIDENT INVESTIGATION SHOWED EVIDENCE THAT THE TAIL ROTOR BLADES ENTERED LOOSE SNOW AND WERE SUBJECTED TO RAPID DECELERATION. THE SHAFT HAD SHEARED UNDER APPLIED TORQUE.
NTSB Probable Cause
THE SELECTION OF AN UNSUITABLE LANDING SITE BY THE PILOT, RESULTING IN TAIL ROTOR CONTACT WITH THE TERRAIN AND SHEARING OF THE TAIL ROTOR DRIVESHAFT.
Full Narrative
THE COMMERCIAL PLT FLEW A RESCUE TEAM TO A MOUNTAIN AVALANCHE AREA. THE TEAM DEPLANED AND DURING THE UNLOADING PROCEDURE THE HELICOPTER SETTLED BACKWARDS INTO LOOSE SNOW. THE PLT ADDED COLLECTIVE PITCH AND ATTEMPTED TO HOVER. AS THE HELICOPTER LEFT THE GROUND, AN UNCOMMANDED RIGHT SPIN BEGAN. THE PLT PERFORMED A HOVERING AUTOROTATION 30 FEET AWAY FROM THE GROUND PERSONNEL. AT TOUCHDOWN THE TAIL BOOM ENTERED DEEP SNOW AND THE ACFT CAME TO REST NOSE HIGH. THE PLT DISCOVERED THE TAIL ROTOR SHAFT HAD BROKEN FORWARD OF THE TAIL ROTOR GEAR BOX. A POST ACCIDENT INVESTIGATION SHOWED EVIDENCE THAT THE TAIL ROTOR BLADES ENTERED LOOSE SNOW AND WERE SUBJECTED TO RAPID DECELERATION. THE SHAFT HAD SHEARED UNDER APPLIED TORQUE.
Flight
Event TypeAccident
Event Time14:27 MST
Nearest Airport0nm N
Runway0
Flight Plan FiledCvfr
Aircraft FireNo
Aircraft ExplosionNo
Aircraft
AircraftBell 206B III
Tail NumberN16733
Aircraft CategoryHeli
DamageSubstantial
OperatorAvman
Operating RulePart 91
Engines1
Engine TypeTurboshaft
Engine DetailsAllison · 250-C20B · Turboshaft · 420
Seats5
People & Injuries
Injury SummaryNo injuries (1 uninjured)
Fatal0
Serious0
Minor0
Uninjured1
Total1
Crew 1Age 43 · Second Class
Conditions
ConditionsVMC
LightDaylight
Wind270° @ 10 kt, gusting 15 kt
Visibility50 sm
CeilingNone
Temperature / Dew Point19 C / 0 C
Altimeter30.00 inHg
Weather SourcePILO